Digital camera and image capturing method

ABSTRACT

A digital camera and an image capturing method for photographing at least one object in the digital camera. An image is sensed, and an eye-gazing detection process is accordingly preformed on the image to detect an eye-gazing direction of at least one pair of eyes of the at least one object. It is determined whether the eye-gazing direction meets a gazing criterion. If the eye-gazing direction meets the gazing criterion, an application of the digital camera is triggered.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No.12/419,408, filed Apr. 7, 2009, now U.S. Pat. No. 8,482,626 and entitled“Digital Camera and Image Capturing Method,” the entirety of which isincorporated herein by reference.

BACKGROUND

1. Technical Field

The disclosed embodiments relate to digital cameras, and in particular,to an image capturing method employing eye-gazing detection to triggervarious applications.

2. Description of the Related Art

Digital cameras are designated to be compact and cost effective, thusthe computation power is limited due to power consumption and costissues. For most of the digital cameras, response time of a digitalcamera may not be as fast as high end devices, thus the performance isaffected by shutter latency. Shutter latency means a period of responsetime between button triggering and image capturing. Due to the shutterlatency, it is difficult to capture a picture at the right timing,particularly when the object to be photographed is a moving livingspecies such as humans or pets.

Furthermore, most users desire to capture the eyes of living speciesbeing photographed. In other words, the best time to take a picture maybe when the eyes of living species being photographed are gazing at thedigital camera. However, such a picture is difficult to acquire;especially when the object being photographed is a large group ofpeople, a kid or a pet since they are, however, uncontrollable. Thus, itis desirable to develop an improved function for digital cameras toovercome above-mentioned problems.

SUMMARY

An exemplary embodiment of an image capturing method is provided forphotographing at least one object in a digital camera. An image is firstsensed, and an eye-gazing detection process is performed on the image todetect an eye-gazing direction of at least one pair of eyes of the atleast one object. It is determined whether the eye-gazing directionmeets a gazing criterion. If the eye-gazing direction meets the gazingcriterion, an application of the digital camera is triggered.

Another exemplary embodiment of a digital camera is provided forphotographing at least one object. In the digital camera, a photo sensormodule senses an image. A user interface includes a display operative todisplay the image. A memory device is employed for storage of the image.A processor is coupled to the photo sensor module, memory device, andthe user interface, performing the eye-gazing detection process on theimage, determining whether the eye-gazing direction meets a gazingcriterion, and triggering an application of the digital camera if theeye-gazing direction has met a gazing criterion. A detailed descriptionis given in the following embodiments with reference to the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments of the invention can be more fully understood by readingthe subsequent detailed description and examples with references made tothe accompanying drawings, wherein:

FIG. 1 a shows a digital camera according to an embodiment of theinvention;

FIG. 1 b illustrates a flowchart of an image capturing method accordingto an embodiment of the invention; and

FIG. 2 is a flowchart of an eye-gazing detection process according to anembodiment of the invention.

DETAILED DESCRIPTION

In the following detailed description, for purposes of explanation,numerous specific details are set forth in order to provide a thoroughunderstanding of the present invention. It will be apparent, however,that the present invention may be practiced without these specificdetails. In other instances, well-known structures and devices areschematically shown in order to simplify the drawing.

To take a picture at right time when eyes of objects being photographedare gazing at a digital camera, a real time monitoring mechanism may beimplemented to assist a photographer.

FIG. 1 a shows an embodiment of a digital camera 100 according to theinvention. A user interface 104 typically comprises a panel (not shown)for user control, a trigger button 114 for taking a picture, and adisplay 124. A photo sensor module 102 includes a lens, a shutter and aphoto sensor such as a Charge Coupled Device (CCD) or a ComplementaryMetal-Oxide Semiconductor (CMOS) (not shown) dedicated to convertreceived light into digital signals, and that is how an image is sensed.The photo sensor may sense an image in various mechanisms. For example,in traditional shutter mechanism, the trigger button 114 is used totrigger the shutter in the photo sensor module 102 to open an aperturefor a brief period. The brief period is conventionally referred to as anexposure time. The photo sensor is thereby exposed to the lights throughthe aperture for the exposure time duration, and such that the lightsare converted into digital signals.

Live viewing is also a prevalent mechanism. In a live view mode, theshutter is kept open, and the photo sensor is continuously activated tocapture images of every moment, generally at a rate of 30 frames persecond (FPS). The mode is so called “live view” because the images canbe displayed instantly on the display 124, presenting as live movingpictures. When the trigger button 114 is triggered in the live viewmode, an image corresponding to the moment is captured and stored intothe memory device 108. The memory device 108 can be various knowndevices such as Compact Flash (CF) card, Secure Digital (SD) Card or ahard disk drive.

In the digital camera 100, a processor 106 connected to the photo sensormodule 102, the user interface 104 and the memory device 108, controlsvarious functions. For example, an eye-gazing detection process isperformed by the processor 106, to detect at least one eye-gazingdirection of at least one pair of eyes of objects. The processor 106 mayreceive a trigger signal from the user interface 104 to initialize theeye-gazing detection process, and trigger a particular application ofthe digital camera 100 if the eye-gazing direction has met a gazingcriterion. Generally, in order to provide instant response to thescenes, the eye-gazing detection is performed in live view mode. Adetailed embodiment is described in the following flowcharts.

FIG. 1 b is a flowchart of an embodiment of the image capturing methodimplemented on the digital camera 100. Please note that if the result issubstantially the same, the steps are not required to be executed in theexact order shown in FIG. 1 b. In step S101, the digital camera 100 isinitialized, wherein an eye-gazing detection mechanism is installed inthe processor 106 as a firmware or application specific integrated chip(ASIC). In practice, the photo sensor module 102 of the digital camera100 continuously senses an image after being powered up. To be precise,the digital camera 100 continuously samples photo signals at a certainframe rate to generate a consecutively updating image. As known, theimage is usually displayed on a display 124 of the digital camera 100,facilitating users to composite a desired picture. Thus, the eye-gazingdetection may be a sub-routine executed by the processor 106 toconstantly monitor the image for triggering designated applications.

In step S105, the eye-gazing detection process is preformed on the imageto detect at least one eye-gazing direction of at least one pair ofeyes. In an embodiment of the invention, the eye-gazing detectionprocess can be performed when a trigger button 114 in the digital camera100 is pressed. Alternatively, the eye-gazing detection process can beperformed instantly after the digital camera 100 is powered up. Asknown, face detection is a prevailing technology bundled with variousapplications such as focusing on faces and smile capturing. Theinvention provides further applications based on the detected eye-gazingdirections, which will be described in the following. In step S107, thesensed image is sent from the photo sensor module 102 to the processor106, allowing the processor 106 to determine whether the eye-gazingdirection meets a gazing criterion. The gazing criterion to trigger anapplication is programmable. If the gazing criterion is not met in stepS107, step S109 is performed. Otherwise, if the gazing criterion is met,step S111 is performed.

In step S109, an indication signal is asserted through the userinterface 104, allowing objects being photographed to adjust their posesaccordingly. The indication signal may be a voice signal, a blinking LEDor a displayed character. For example, when a group picture is to betaken, the digital camera 100 may indicate the number of pairs of eyesdetected, or raise an alarm to attract the objects being photographed(particularly for pets or kids), thereby increasing the success rate oftaking a picture when all eyes the objects being photographed are gazingat the camera. After the indication signal is asserted in step S109, theimage capturing method goes back to step S105 to perform the eye-gazingdetection process for detecting the eye-gazing direction and thendetermine whether the detected eye-gazing direction meets the gazingcriterion in step S107 again. Please note that step S109 is optionalthat the image capturing method may go to step S105 directly if thedetected eye-gazing direction do not meet the gazing criterion in S107.

In step S111, if the eye-gazing direction has met the gazing criterion,a particular application can be triggered. The particular application,for example, may implement instant photo capture upon the eyes gazingwith the digital camera. However, the invention is not limited to thisfunction. Various applications may also be implemented based on theeye-gazing directions detected. For example, a particular applicationmay be implemented to assert an indication signal when the gazingcriterion is met. In addition to the described example wherein theshutter is triggered to take a photo upon eye-gazing, there are manycircumstances that may be facilitated by the eye-gazing detection. Forexample, an auto focusing application can be provided to focus on anypair of gazed eyes. If there are many people in the picture, the lensfocus may be automatically focused to the ones who gaze at the digitalcamera. Furthermore, since the eye-gazing direction is detectable, thelens focus may be automatically focused on an object on the directionwhere the eyes are gazing. An auto shuttering application can also beprovided, in which the shutter in the photo sensor module 102 isautomatically triggered upon all or a number of people gazing upon thedigital camera, allowing unattended shutter triggering to beimplemented.

Furthermore, the image may be captured and saved as a photograph uponall eyes being detected and facing to the digital camera. If the digitalcamera is in a video mode, the image may be recorded as a movingpicture. Meanwhile, when the gazing criterion is met, the digital cameramay only indicate that criterion is met to photographers and objectsbeing photographed. All the above-mentioned applications can beimplemented by the processor 106 in the digital camera with aprogrammable firmware.

The gazing criterion may be configured through the user interface 104before entering the eye-gazing detection process in S105, such as instep S103. Various considerations to configure a gazing criterion arediscussed as follows.

The gazing criterion may define the eye-gazing direction of at least onepair of eyes with respect to the digital camera 100. If required, theeye-gazing direction may also be designated at a specific angle as thegazing criterion to trigger the shutter to take a picture of differentstyles. The eye-gazing direction is detectable using various knownalgorithms, mostly adapted in medical systems for assisting disabledpeople. For example, the eye-gazing direction can be determinedaccording to comparison of locations of face and the pair of eyes withrespect to the camera and location of pupils of the pair of eyes withrespect to the camera. Thus, detailed introduction is not describedherein.

Step S105 is a repetitive process, thus a plurality of detection resultscan form a sequence, such as a trail of consecutive eye-gazingdirections. The trail may feature specific patterns that can berecognized as meaningful gestures, so as to direct the camera to respondwith specific operations accordingly. To implement the gesturerecognition, the gazing criterion may further define a trail pattern tobe compared with the trail of consecutive eye-gazing directions.

The gazing criterion may also define a number of pairs of eyes gazing atthe digital camera 100 if a group of people is to be photographed in onepicture. Since the possibility for all people to simultaneously look atthe digital camera is lower as the number of people increases, thegazing criterion may alternatively define a threshold or a number ofpairs of eyes that are gazing at the digital camera 100. For example,the threshold may be defined as 60%, then, when six people among tenpeople are gazing at the digital camera, the picture is taken.

FIG. 2 is a flowchart of eye-gazing detection process performed in stepS105 according to an embodiment of the invention. Please note that ifthe result is substantially the same, the steps are not required to beexecuted in the exact order shown in FIG. 2. The eye-gazing detectionprocess is a series of algorithms. There are presently various knownalgorithms implementing face detection and eye tracking, and theinvention provides further applications based thereon. In step S201, theeye-gazing detection is initialized. To detect eyes, the digital cameramust sense a sharp image, thus, focusing is required. In step S203, thedigital camera adjusts its focus to sense a sharp image. As known, in animage, out of focus objects are blurred, and the blurred effect is alsoreferred to as “bokeh”. For large aperture lenses and long-rangedlenses, bokeh occurs in the image while only the object on the focus issharp. Since it is difficult to analyze blurred portion of an image, theeye-gazing detection process may be performed only within the focusrange. Thus, the focus range is a parameter to be concerned with.Generally, a typical digital camera is capable of auto focusing (AF).For example, a user can define a focus criterion through the userinterface 104 to specify that the eye-gazing detection process isperformed on objects within the focus range such as 2 to 5 meters. Inthis case, only faces or eyes within the focus range of 2 to 5 metersare to be detected or located. Thus, faces or eyes of objects out of therange would be ignored.

In step S205, faces within the image are detected. Since there arevarious known technologies to implement face detection, detailedintroduction is omitted. In step S207, at least one pair of eyes of thedetected faces in the image is located. Please note that step S205 is anoptional step, so step S207 may be performed directly following stepS203 to locate at least one pair of eyes within the image. Further,through appropriate programming, not only human eyes are detectable.Other animals such as dog eyes and cat eyes may also be applicable.

In step S209, pupils of the pair of eyes are analyzed to determine theeye-gazing direction. As a simplest example, one eye-gazing directiondetected to be held over a particular period, can be seen as a gazingcriterion match. Nevertheless, in practice, consecutive eye-gazingactivities are considered as parameters to find the trigger. Forexample, a plurality of eye-gazing directions sampled over a period oftime may form a trail pattern such as a circular, an up and down trail,and so on. A trail of consecutive eye-gazing directions can be assessedas a gesture that expresses user thoughts. Other activities such aseyelids blinking, closing or remaining wide opened may also beconsidered as parameters to find the trigger. For example, when a personbeing photographed blinks his/her eyes twice, a particular applicationcan be triggered, such as taking the picture, or recording a motionpicture.

Based on a properly defined gazing criterion, when the eye-gazingactivities are detected as having blinked twice, circling around, orrapidly looking up and down, a particular camera application may betriggered, such as turning on the flash light or filming a movingpicture. In other words, based on the eye-gazing detection technology,various applications as described in step S111 can be triggered.

The invention is particularly adaptable in a digital camera, or aportable device capable of photography. The capturing method can beimplemented in software or a dedicated chip. Moreover, if thecomputation power allows, the eye-gazing detection can incorporate amotion predictor to trigger the shutter in advance to compensate for theshutter latency. This is particularly useful when the object to bephotographed moves fast.

While the invention has been described by way of example and in terms ofpreferred embodiment, it is to be understood that the invention is notlimited thereto. On the contrary, it is intended to cover variousmodifications and similar arrangements (as would be apparent to thoseskilled in the art). Therefore, the scope of the appended claims shouldbe accorded the broadest interpretation so as to encompass all suchmodifications and similar arrangements.

What is claimed is:
 1. An image processing method for a digital camera,comprising: sensing an image; performing an eye-gazing detection processon the image to detect an eye-gazing direction of at least one eye of atleast one object in the image; determining whether the eye-gazingdirection meets a gazing criterion, wherein the gazing criterion definesa specific angle of the eye-gazing direction of the at least one eye ofthe at least one object with respect to the digital camera, and whereinthe eye-gazing direction is determined by analyzing pupils of the atleast one eye; and triggering an application of the digital camera inresponse to the eye-gazing direction meeting the gazing criterion. 2.The image processing method as claimed in claim 1, further comprising,asserting an indication signal if the gazing criterion is not metthereby allowing the at least one object to react for meeting the gazingcriterion.
 3. The image processing method as claimed in claim 1, whereinthe indication signal is a voice signal, a blinking LED or a displayedcharacter.
 4. The image processing method as claimed in claim 1, furthercomprising configuring the gazing criterion prior to performing theeye-gazing detection process.
 5. The image processing method as claimedin claim 1, wherein the gazing criterion defines a number of the atleast one of eyes gazing at the digital camera.
 6. The image processingmethod as claimed in claim 1, wherein the eye-gazing detection processis performed when a trigger button of the digital camera is pressed. 7.The image processing method as claimed in claim 1, wherein: theeye-gazing detection process further comprises detecting at least oneface in the image; and locating the at least one eye within the detectedfaces.
 8. The image processing method as claimed in claim 1, wherein thedigital camera captures the image, stores the image, records the imageas a moving picture, or asserts an indication signal indicating that thegazing criterion is met as the triggered application of the digitalcamera in response to the eye-gazing direction meeting the gazingcriterion.
 9. A digital camera comprising: a photo sensor module,operative to sense an image; a user interface, comprising: a display,operative to display the image; a memory device, for storage of theimage; a processor, coupled to the photo sensor module, memory device,and user interface, performing an eye-gazing detection process on theimage to detect an eye-gazing direction of at least one eye of at leastone object, determining whether the eye-gazing direction meets a gazingcriterion, and triggering an application of the digital camera inresponse to the eye-gazing direction meeting a gazing criterion, whereinthe gazing criterion defines a specific angle of the eye-gazingdirection of the pair of eyes of the at least one object with respect tothe digital camera; and wherein the eye-gazing direction is determinedby analyzing pupils of the at least one pair of eyes.
 10. The digitalcamera as claimed in claim 9, wherein the user interface asserts anindication signal if the gazing criterion is not met, thereby allowingthe at least one object to react for meeting the gazing criterion. 11.The digital camera as claimed in claim 9, wherein the indication signalis a voice signal, a blinking LED or a displayed character.
 12. Thedigital camera as claimed in claim 9, wherein the gazing criterion isconfigured through the user interface.
 13. The digital camera as claimedin claim 9, wherein the gazing criterion defines a number of at leastone eye gazing at the digital camera.
 14. The digital camera as claimedin claim 9, wherein the processor performs the eye-gazing detectionprocess to further: detect at least one face in the image; and locatethe at least one eye within the detected at least one face.
 15. Thedigital camera as claimed in claim 9, wherein the processor triggers thedigital camera to capture the image, store the image into the memorydevice, record the image as a moving picture, or assert an indicationsignal through the user interface for indicating that the gazingcriterion is met if the eye-gazing direction meets the gazing criterion.